In a small bowl, combine the yuzu kosho with the ginger, garlic, lemongrass, coriander and oil.
Spread half of the pesto on the prawns and let stand for 10 minutes.
Light a grill or preheat a grill pan. Grill the prawns over high heat, turning once, until lightly charred and cooked through about 4 minutes
Transfer the prawns to plates and serve with the remaining pesto.
The yuzu kosho pesto can be refrigerated for up to 3 days.